<p>According to researchers from Quebec, Illinois, and Texas, to prevent the spread of Covid-19 indoors, the two metres physical distancing guideline is not enough without masks.</p>.<p>The findings of the study were published in the journal Building and Environment.</p>.<p>Wearing a mask indoors can reduce the contamination range of airborne particles by about 67 per cent.</p>.<p>In this study, researchers found that when people are unmasked, more than 70 per cent of airborne particles pass the two metres threshold within 30 seconds. By contrast, less than 1 per cent of particles cross the two-metre mark if masks are worn.</p>